Jared Green: In your book Urbanism in the Age of Climate Changeyou argue that "urbanism is the foundation for a low-carbon future" and the most cost-effective solution to climate change. What is urbanism? Why is it the solution?

Peter Calthorpe: Good urbanism has these three basic principles. One is human scale, which has to do with designing public spaces around the pedestrian rather than the car. Diversity is another key ingredient and basically says that you have to have a range of uses mixed together – you can't isolate housing and shopping and employment into separate zones – but also you need a diverse population; you can't isolate age groups, income groups and family types. Those two fundamental principles, human scale and diversity, are always at the heart of urbanism, whether it’s in a city context or a small town context.

The third principle, which wasn’t historically part of urbanism, is conservation and restoration. It used to be that a city would pretty much plough over whatever got in its way, whether it was wetlands or any aspect of the natural environment. There needs to be greater sensitivity to the ecological context. Cities also remake themselves – they demolish and rebuild all the time – and I think that’s a very important part of urbanism. The resilience of the urban fabric is that it can be renewed and redone. However, a greater sensitivity to history, historic resources and cultural resources has to be part of urbanism now. So, those three principles are at the heart of what I mean when I say urbanism. That then easily translates into what would be the best foundation for a low carbon future.

The urban solution involves both technology and design. For example, we will need to dramatically reduce the number of miles we drive as well as develop less carbon-intensive vehicles. It will mean living and working in buildings that demand significantly less energy as well as powering them with renewable sources. It will involve the kinds of food we eat, the kinds of homes we build, the ways we travel and the kinds of communities we inhabit. It will certainly involve giving up the idea of any single “silver bullet” solution (whether solar or nuclear, conservation or carbon capture, adaptation or mitigation) and understand that such a transformation will involve all of the above – and, perhaps most important, that they are all interdependent.

JG: You advocate a whole systems rather than a checklist approach for redeveloping communities, reducing energy usage and addressing climate change. In practical terms, how can a systems approach be used?

PC: The problem with the environmentalists that are advocating for action on climate change now is they tend to create a checklist of technologies as a solution. If you look at Al Gore’s book [Our Choice], it is just a compendium of different technologies that can be stacked up one on the other to solve the problem. It doesn’t really change the kinds of cities we live in, the kinds of communities we inhabit. It doesn’t address our lifestyle. It basically says we can solve it all with a new piece of technology. It’s the thinking that the electric car is the single solution, rather than reducing the amount of travel that we need to live our lives in a healthy and robust way. In the end it will take both.

The whole systems approach looks at a broad range of problems that need to be addressed and tries to find solutions that synthesise those problems and begin to find common solutions.

The engineering mentality is always to take one issue at a time, and because of that, we lose the possibility of being real good designers. Take for example, streets. If you approach streets with an engineering mentality and only focus on how you move the most number of cars most efficiently, you get one type of street. If you think of the street as having many agendas, like walking, biking, cars, lingering, meeting, the ecology of street trees (both in terms of micro climate and as habitat), when you begin to think about all the different functions of a street and you design for all of them rather than one, you get a much richer environment and once again you solve many problems simultaneously.

JG: You say regional plans are needed to put in place more progressive policies that preserve open space. Why is open space so important? What is the relationship between open space and density, which you say is also critical to achieving sustainable development?

PC: You have several issues packed together there. One is that the solution isn’t so much that everybody needs to live in a city, but people need to live in regions that offer a huge range of living environments and community types. The question is: what knits all that together?

Transit is one substructure that can knit it together in a healthy, environmental way, but open space systems are the other. We now tend to live in regional communities. Our job and economic opportunities are regional; they’re not within any one jurisdiction. Most of our environmental impacts are regional – air-quality impacts obviously occur over a much larger geography than individual towns and cities and counties. Water quality is the same and, of course, underlying all that is an open space network that respects and protects the most valuable natural resources in an area, and then uses those as a framework, as the kind of common ground at the regional scale, to reinforce that common identity.

Quite frankly, many people see themselves as fragments, living in small, isolated places in the context of a zero-sum game – my suburban town doesn’t need to do affordable housing because some other town or downtown is doing it. That parochial view needs to be broken down by things that really unify and make us citizens of the region. The respect for the environmental context is what creates identity and common ground at the regional scale.

There are other things at the regional scale: the diversity of economy, and the kinds of linkages and transportation nexus that happens are all really key to creating sustainable communities. So you can't solve the problem at the scale of the individual houses, much as people would like to think just putting some solar panels up and buying a different car will solve the problem. You can't really solve the problem at the scale of the individual, town or county. The regional scale is actually the important one in terms of the global economic context. It's also the scale at which we can solve the most critical environmental issues.

JG: Transit oriented development (TOD), an idea you developed is in your words, "regional planning, city revitalisation, suburban renewal and walkable neighbourhoods rolled into one.” In layman’s terms, why is TOD so central to sustainable community development?

PC: The idea of transit oriented development (TOD) is really central because it links the region together in ways that we need. The idea that everybody is going to live, work, and play in the same neighbourhood is not realistic. People are always going to travel to their best job opportunity. The question is: what travel choices do they have?

The idea of transit oriented development is very simply that you need to conveniently walk to local destinations and transit opportunities that connect you to all sorts of regional opportunities, whether it’s jobs or unique regional cultural or environmental resources. Living within walking distance of transit and creating a neighbourhood around the transit that is convivial to walk in is at the foundation of how you would reform our existing suburbs.

JG: One sustainability indicator you view as critical is vehicle miles travelled (VMT), which policymakers and players can map per household in different communities. Why do low rates of VMT tell you so much?

PC: It's a very important indicator because different places can lead to many different outcomes in terms of travel behaviour. You can have areas where people use lots of transit, other areas where they bike a lot and then, in some of our densest, urban areas, pedestrian and walking becomes dominant. The key here is all of those are benign alternatives. The key is just to reduce VMT, because VMT represents carbon emissions, oil dependence and the need for a lot of asphalt and roads, and a lot of construction costs. VMT represents the need for huge parking structures or parking fields, the diminution of the human scale and the pedestrian environment. There are many ways to reduce it.

VMT is, of course, what leads to most of the negative impacts of our built environment, whether it’s air quality and the impact on respiratory disease, or the amount we walk and the obesity that comes out of that, or the amount of land we consume per household and the amount of asphalt we have to lay down, and therefore the amount of runoff and water degradation we create, or the quantity of energy we need and all the implications that represents.

JG: Lastly, is there a popular demand for the new “green urbanism” approach you propose?

PC: The market forces already at work will make urbanism the core of the next generation of growth in America. The need for a different housing – more compact urban housing – is already manifest in the market. We can frame that as good urbanism, creating beautiful, walkable streets and supporting it with adequate transit and making sure that they are truly mixed-use environments.

The public sector has to create the right kind of plans to satisfy the market demand. The bottom line is [in the United States] there’s a large market for townhouses, but who wants to live in a townhouse without a town? And the danger is that, unless we create these great urban places, the market demand for higher density housing won’t be realised in quite the way that it should. Standing in the way are local communities that are simplistically against change, fearful of change, diversity, and infill and even revitalisation. It’s not going to be easy, but at least at this stage we have the ideas and the design principles are clearly in hand.

There needs to be education so the next generation that’s out looking for their first home can understand there are choices other than driving great distances to get an affordable house in the suburbs. Underneath it all, we need to rethink the hierarchy at the regional scale – the range of choices and how they are connected. We need regional plans that do a really good job of environmental conservation, transit and an equitable distribution of affordable housing.
Peter Calthorpe is author of Urbanism in the Age of Climate Change, principal of Calthorpe Associates and a founder of Congress for New Urbanism (CNU).

City populations swelling with displaced people

This article does not reflect that cities are already having to cater for the flow of rural poor displaced by land grabs and climate change - and might be swamped by migrants if not sea-level rise.

Those in the USA will be particularly constrained by the carbon debt which the USA owes the poor around the world.

Greenhouse gas emissions associated with the lifecycle of the buildings and infrastructure of cities today should be taken into account during planning and approvals. Design and construction should be for the long term.